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Re: Pteros might be dinos?!? Oh no ...



On Tue, Nov 10, 2009 at 5:17 PM, Tim Williams <tijawi@yahoo.com> wrote:
>
> With the caveat that I'm not a PhyloCode expert (I've just read the thing),

That makes you more of an expert than most of the people who have
commented on it! :)

> (2) Novas actually defined Dinosauria as Herrerasauridae + Saurischia + 
> Ornithischia. ÂMy reading of the PhyloCode leads me to believe that only 
> species or specimens can be used as specifiers.

Also apomorphies, for apomorphy-based definitions.

Mike Taylor has argued that we should take a lenient view of these
early definitions:
http://www.miketaylor.org.uk/dino/pubs/taylor2007/abstract.html
This one is quite easy to make compliant with PhyloCode rules: simply
change the taxa to their type species (Herrersaurus ischigualastensis)
or their internal specifiers (Megalosaurus bucklandii, Iguanodon
bernissartensis).

On Tue, Nov 10, 2009 at 7:03 PM, Augusto Haro <augustoharo@gmail.com> wrote:
>
> Thanks Michael and Tim for the responses... I do not get what is an
> "essential member of the Dinosauria" Those taxa which were considered
> members of a larger taxon when the latter was erected?

I mean that the concept of "Dinosauria" has never relied on the
inclusion of Herrerasauridae (except, of course, in Novas'
definition). It has generally relied on characters or on the inclusion
of other taxa.

The PhyloCode would not disallow Novas' definition, as emended above.
But what's the point of including H. ischigualastensis as a specifier?
Why not just make it Clade(M. bucklandii + I. bernissartensis)? What
does the addition of H. ischigualastensis buy us?

-- 
T. Michael Keesey
Technical Consultant and Developer, Internet Technologies
Glendale, California
http://tmkeesey.net/